There are a wide variety of electronic and mechanical devices for monitoring and treating patients' medical conditions. In some examples, depending on the underlying medical condition being monitored or treated, medical devices such as cardiac pacemakers or defibrillators may be surgically implanted or connected externally to the patient.
One of the most deadly cardiac arrhythmias is ventricular fibrillation, which occurs when the normal, regular electrical impulses are replaced by irregular and rapid impulses, causing the heart muscle to stop normal contractions and to begin to quiver. Normal blood flow ceases, and organ damage or death can result in minutes if normal heart contractions are not restored. Because the victim has no perceptible warning of the impending fibrillation, death often occurs before the necessary medical assistance can arrive. Other cardiac arrhythmias can include excessively slow heart rates known as bradycardia.
Implantable or external pacemakers and defibrillators (such as automated external defibrillators or AEDs) have significantly improved the ability to treat these otherwise life-threatening conditions. Such devices operate by applying corrective electrical pulses directly to the patient's heart. For example, bradycardia can be corrected through the use of an implanted or external pacemaker device. Ventricular fibrillation can be treated by an implanted or external defibrillator.
Continuous monitoring devices operate by substantially continuously monitoring the patient's heart for treatable arrhythmias and, when such is detected, the device applies corrective electrical pulses directly to the heart. Wearable pacing devices and/or defibrillators have been developed for a certain population of patients, e.g., those that may have recently experienced a heart attack, that are susceptible to heart arrhythmias and are at temporary risk of sudden death, or that are awaiting an implantable device. For example, to protect against cardiac arrest and other cardiac health ailments, some at-risk subjects may use a non-invasive bodily-attached ambulatory medical monitoring and treatment device, such as the LifeVest® wearable cardioverter defibrillator available from ZOLL® Medical Corporation. To remain protected, the subject wears the device nearly continuously while going about their normal daily activities, while awake, and while asleep.
Non-therapeutic monitoring medical devices, e.g., cardiac event monitors, collect cardiac information, such as a patient electrocardiogram (ECG) recordings, and provide the information to an external network or remote server on a periodic basis. Mobile cardiac telemetry devices monitor patient physiological information, such as ECG, and can send data aperiodically, such as when a particular triggering event is identified.